Polymer matrix composite (PMC) materials are widely used in a number of applications. For example, such composite materials are being increasingly used in high-performance aerospace structures such as parts of airplanes and automobiles as high-strength, low weight materials to replace metals. PMC materials contain reinforcement fibers, such as carbon, glass and aramid fibers, embedded in a polymeric matrix material. The PMC materials exhibit good mechanical properties (e.g., strength, stiffness, toughness), as well as enable a wide processing temperature window and ease of manufacture, making them well suited for aerospace applications.
Methods for producing fiber-reinforced composite materials include a method of forming prepregs by impregnating sheet-like reinforcing fibers with an uncured matrix resin. This method is often called “prepregging” method. Multiple plies of the prepregs are laminated, consolidated and subsequently cured to form a composite part. Alternatively, composite parts may be formed using a resin transfer molding (RTM) method, which involves injecting a liquid resin into a preform of reinforcing fibers disposed in or on a mold and subsequently heating the resin-infused preform to cure the resin.
As the matrix resins used in PMC materials, thermosetting resins are mainly used because of their high solvent resistance and thermal resistance. Epoxy resins are often used because of the adhesiveness between the epoxy resins and the reinforcing fibers, and the mechanical properties such as strength and stiffness of the composite material obtained.